ELECTROPHORETIC SAMPLE PRETREATMENT TECHNIQUES COUPLED ONLINE WITH COLUMN LIQUID-CHROMATOGRAPHY

The on-line coupling of zone electrophoretic and isotachophoretic sample treatment with column liquid chromatography (LC) is described. The electrophoretic sample treatment methods are carried out in free solution. Zone electrophoretic sample treatment (ZEST) of 20 mm3 of sample takes about 20 min. The applicability of ZEST to environmental analyses is demonstrated with the determination of bentazone in water from the river Rhine. Preliminary results are presented for the on-line coupling of isotachophoresis (ITP) with LC, using a single switching valve. With ITP 30 MM3 sample volumes, which can be concentrated to an injection volume of 5 mm3 can be treated within 17 min.